ZIF-derived High Specific Surface Area Npcs Prepared By Metal Salts And Their Adsorption Applications

Dye effluents are toxic and carcinogenic to humans and aquatic organisms.Adsorption technology has been widely used for decades as a simple and effective method to remove dyes from aqueous solution.Many researchers have attempted to find or design alternative materials for dye adsorption.Zeolite imidazole ester skeleton materials（ZIFs）have high specific surface area,high porosity,good thermal and chemical stability and structural diversity of the customizable inherent advantages,for the preparation of porous carbon materials with different structures and different decoration provided the infinite possibility.ZIFs-derived nanoporous carbon materials（NPCs）inherit the advantages of large specific surface area and high porosity of ZIFs,and can be used to adsorb pollutants in the environment,which has attracted extensive attention in recent years.In this study,ZIF-8 was synthesized by room temperature synthesis method,and the precursor metal salt@ZIF-8 was prepared by constant volume impregnation method.ZIF-8 was calcined in a tubular furnace at 800～1000℃in an inert gas atmosphere to obtain ZIF-8 nanoporous carbon materials.Nitrogen adsorption and desorption analysis shows that Zn Cl₂ loading can significantly increase the specific surface area of ZIF-8-based nanoporous carbon.By modifying the carbonization temperature and Zn Cl₂loading,the specific surface area of NPC-0.5-1000 and NPC-1-1000 can reach 2780 m²/g and 2866 m²/g,respectively.The pore volumes were 0.63 cm³/g and 0.64 cm³/g,respectively,indicating that the best carbonization temperature and Zn Cl₂ loading capacity of the prepared ZIF-8-based nanoporous carbon with high specific surface area were 1000℃and 0.5 g,respectively.XRD analysis shows that the prepared ZIF-8 has high crystallinity and is a single pure phase,and the prepared ZIF-8 nanoporous carbon is amorphous carbon;Shown from SEM analysis,The morphology of NPC-0.5-1000 and NPC-1-1000 is roughly spherical granular structure,and presents a situation of accumulation;Shown from FTIR analysis,the adsorption of Rh B by NPC-1-1000belongs to pore adsorption;Shown from XPS analysis,pyridine nitrogen in NPC-1-1000is favorable for the adsorption.In the adsorption experiment,NPC-1-800,NPC-0-1000,NPC-1-900,NPC-0.5-1000and NPC-1-1000 were used as adsorbents.Rhodamine B（Rh B）was selected as absorbate by comparison.Six influencing factors showed that the most suitable dosage of absorbate was 0.01 g;When p H is controlled at 6,the adsorption effect can be improved and the maximum adsorption amount can be obtained The adsorption capacity of NPC-0.5-1000and NPC-1-1000 can reach 2000 mg/g in the first 3-5 min of adsorption.The adsorption capacity of nanoporous carbon increases with the increase of temperature,and the adsorption reaction is an endothermic reaction.With the increase of K⁺and Cl^-concentration,the adsorption capacity increases slightly.The adsorption mechanism of ZIF-8 based nanoporous carbon can be explained by Langmuir isotherm model.The adsorption of Rh B by NPC-1-800,NPC-1-900,NPC-0.5-1000 and NPC-1-1000 follows the pseudo-second-order kinetic model,and the adsorption of Rh B by NPC-0-1000follows the pseudo-first-order kinetic model.NPC-1-1000 showed good cyclic regeneration after 5 cycles.The maximum adsorption capacity of NPC-1-1000 can reach5177 mg/g.